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O efeito Raman ressonante do complexo (NH4)4Mo2Cl8.NH4Cl.H2O, contendo o íon Mo2Cl84-, foi estudado tanto na temperatura ambiente como na de nitrogênio líquido. Com base nos resultados obtidos mostra-se que a explicação previamente oferecida por outros autores para o aparecimento de ressonância com excitação em 568,2 nm não é correta. É sugerida uma explicação diferente para este comportamento baseada nos espectros Raman e de absorção. A transferência de elétron fotoestimulada no íon complexo (NH3)5RuII-pz-CuII foi comprovada através do estudo do efeito Raman ressonante. Com base nos espectros Raman obtidos em condições de ressonância e também nas medidas de polarização, o estado eletrônico excitado envolvido foi caraterizado. Os perfis de excitação para v1 e 2vl do íon RuO42- em solução aquosa foram obtidos usando diversas radiações excitantes. Os perfis mostraram uma desintensificação das intensidades Raman pré-ressonantes na região da transição interna do íon. O efeito foi interpretado usando o tratamento proposto por Stein e col. para o efeito Raman anti-ressonante. / The Raman resonance effect of the complex (NH4)4Mo2Cl8.NH4Cl.H2O, containing the Mo2Cl84- ion, was investigated at both room and liquid nitrogen temperatures. On basis of the obtained results it is shown that the previous explanation given by others authors for the resonance observed with 568.2 nm excitation is not a correct one. A different explanation for this behaviour is suggested, based on the Raman and absorption spectra. The photostimulated electron transfer in the complex ion (NH3)5RuII-pz-CuII was confirmed trough the investigation of its Raman ressonance effect. The Raman ressonance spectra and the polarization measurements had enabled the characterization of the electronic excited state involved in the transition. The excitation profiles of v1 and 2v1 of the RuO42- ion in aqueous solution were obtained using several exciting radiations. The profiles present a de-enhancement of the pre-resonant Raman intensities in the region of the ion internal transition. This effect was interpreted using the treatment proposed by Stein et al. for the anti-resonance Raman effect.

A bulk silicon temperature sensor is fabricated in this work. The objective is to develop a low-cost high resolution temperature sensor. The target applications are a Conductivity-Temperature-Depth (CTD) sensor for oceanic applications and a magnetocaloric microcooler. The properties of silicon are modified by thermal diffusion of gold. Gold is a fast diffuser in silicon and its diffusion contributes to the increase in resistivity of silicon. The addition of gold to n-type silicon creates a negative temperature coefficient device. The effect of the diffusing environment was investigated by diffusing in oxygen and nitrogen ambient at various temperatures. The influence of area of gold diffusion was also investigated. The effect of temperature on resistance was measured and was used to calibrate the sensor. Although the sensors fabricated in an oxygen environment have an exponential type response, they can be used in the CTD application because of enhanced sensitivity in the 10˚C - 30˚C temperature range. Sensors fabricated in a nitrogen environment are found to have linear response with sensitivity ranging from 7Ω/˚C to 3000Ω/˚C and can be used for both applications. The fabricated sensors have a 0.1˚C resolution.

O efeito Raman ressonante do complexo (NH4)4Mo2Cl8.NH4Cl.H2O, contendo o íon Mo2Cl84-, foi estudado tanto na temperatura ambiente como na de nitrogênio líquido. Com base nos resultados obtidos mostra-se que a explicação previamente oferecida por outros autores para o aparecimento de ressonância com excitação em 568,2 nm não é correta. É sugerida uma explicação diferente para este comportamento baseada nos espectros Raman e de absorção. A transferência de elétron fotoestimulada no íon complexo (NH3)5RuII-pz-CuII foi comprovada através do estudo do efeito Raman ressonante. Com base nos espectros Raman obtidos em condições de ressonância e também nas medidas de polarização, o estado eletrônico excitado envolvido foi caraterizado. Os perfis de excitação para v1 e 2vl do íon RuO42- em solução aquosa foram obtidos usando diversas radiações excitantes. Os perfis mostraram uma desintensificação das intensidades Raman pré-ressonantes na região da transição interna do íon. O efeito foi interpretado usando o tratamento proposto por Stein e col. para o efeito Raman anti-ressonante. / The Raman resonance effect of the complex (NH4)4Mo2Cl8.NH4Cl.H2O, containing the Mo2Cl84- ion, was investigated at both room and liquid nitrogen temperatures. On basis of the obtained results it is shown that the previous explanation given by others authors for the resonance observed with 568.2 nm excitation is not a correct one. A different explanation for this behaviour is suggested, based on the Raman and absorption spectra. The photostimulated electron transfer in the complex ion (NH3)5RuII-pz-CuII was confirmed trough the investigation of its Raman ressonance effect. The Raman ressonance spectra and the polarization measurements had enabled the characterization of the electronic excited state involved in the transition. The excitation profiles of v1 and 2v1 of the RuO42- ion in aqueous solution were obtained using several exciting radiations. The profiles present a de-enhancement of the pre-resonant Raman intensities in the region of the ion internal transition. This effect was interpreted using the treatment proposed by Stein et al. for the anti-resonance Raman effect.

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